This info has been discussed in other forums for other printers but this nube didn't happen upon the info until recently. Seen other potential solutions discussed and the latest TAM branch of Cura has this functionality and some other cool stuff as well. However if you use Simplify3D in addition to Cura like myself, this really is about as simple as it gets and takes longer to read than to do.

First thing, you have to do is download Curl for you OS. I use Windows 10 and downloaded it from the following link.

The download at this link above lean and leaves out all the other things that are normally part of a full curl install but aren't necessary for S3D file upload functionality. Basically the zip file contains the curl.exe and an SSL certificate file.

After downloading the file, unzip it and make note of the path where curl was unzipped to.. That path is need when configuring the command line arguments for post processing box in S3D.

You will also need your API key for Octoprint running on you printer. It can be found in the Octoprint Web interface by selecting the settings icon (wrench in the upper right hand corner) and clicking on the API option. Make sure the API functionality ENABLE box is checked and that you copy the whole API key number. It's longer than what the field displays on the screen,

Next fire up Simplify3D/Edit Process settings (Show Advanced feature enabled), then proceed to the Scripts tab. The format for the command that goes into the "Additional terminal commands for post processing" box at the bottom is similar to the following. Similar but different in that your path where you unzipped curl.exe may be different and the need to use the Octoprint API key and serial number for your specific printer.

Replace the 9's with your specific API key. Replace the x's with your printers serial number. All the other parameters remain as they are. All the punctuation and command option formatting are important so when cutting and pasting your info in, verify you haven't removed or changed any of that.

That's it. Now when you "Prepare the print/Save Toolpaths to disk, after the file is saved, curl takes over and attempts to upload the file to Octoprint running on your printer.

Simplify3D doesn't provide any feed back if the command fails. If it is successful, you should see the gcode file show up in your printers Octoprint file list. The time it takes to upload/show up is related to the size of the gcode file being uploaded and network speed/topology so I would test with a small file to work the kinks out. If you want it to upload the file and start printing, you can change the "print=false" argument to "print=true", but I would hold off doing that initially.

If you don't see the file show up, go back and check the formatting and parameters you configured. Took me a try or two to get it right.